Hydrocracking catalyst

ABSTRACT

Hydrocracking catalysts of improved activity comprising a Group VIB metal hydrogenation component and a crystalline aluminosilicate zeolite base are prepared by adding the Group VIB metal component to the zeolite in an aqueous acidic medium which maintains the Group VIB metal component in an essentially undissolved form. Catalysts prepared in this manner are found to display higher hydrocracking activity than conventional compositions wherein the Group VIB metal component is added to the zeolite by impregnation from an aqueous solution thereof.

United States Patent Young HYDROCRACKING CATALYST Dean Arthur Young,Yorba Linda, Calif.

Union Oil Company of California, Los Angeles, Calif.

Filed: Oct. 20, 1972 Appl. N0.I 299,190

Related US. Application Data inventor:

Assignee:

U.S. Cl. 252/455 Z int. Cl BOlj 11/40 Field of Search 252/455 Z, 437,458

References Cited UNITED STATES PATENTS 2/1968 Rabo et al 252/455 Z June17, 1975 3,392.l08 7/1968 Mason et al. 208/! 11 Primary ExaminerC. DeesAttorney, Agent,. or FirmLannas S. Henderson; Richard C. Hartman; DeanSandford [57] ABSTRACT Hydrocracking catalysts of improved activitycomprising a Group VIB metal hydrogenation component and a crystallinealuminosilicate zeolite base are prepared by adding the Group VIB metalcomponent to the zeolite in an aqueous acidic medium which maintains theGroup VIB metal component in an essentially undissolved form. Catalystsprepared in this manner are found to display higher hydrocrackingactivity than conventional compositions wherein the Group VIB metalcomponent is added to the zeolite by impregnation from an aqueoussolution thereof.

9 Claims, N0 Drawings IIYDRocRAcKING CATALYST RELATED APPLICATIONS Thisapplication is a division of application Ser. No. 209,440, filed Dec.17, 1971, now abandoned, which in turn is a continuation-in-part of mycopending application Ser. No. 869,389, filed Oct. 24, 1969, nowabandoned which in turn is a continuation-in-part of copendingapplication Ser. No. 669,288 filed Sept. 20, 1967, now abandoned.

BACKGROUND AND SUMMARY OF INVENTION This invention relates to improvedhydrocracking catalysts and their preparation and to hydrocrackingprocesses employing the catalysts. Metals of Group VIB, in elementalform or in the form of their oxides or sulfides, have previously beenemployed as hydrogenation components on bases such as alumina andsilicaalumina for hydrocracking operations. More recently, crystallinezeolites have been employed as the base material for catalysts in suchreactions. While these catalysts have proved fairly satisfactory,improved performance, particularly with respect to ability to give ahigh yield of useful product, is much to be desired.

Prior art zeolite catalysts, such as those disclosed in US. Pat. No.3,013,988, comprise a crystalline aluminosilicate zeolite containing aGroup VIB metal, or oxide thereof, dispersed in the internal adsorptionarea of the zeolite. Such a dispersion was believed essential in orderto provide the catalytic material in a form having a high specificsurface suitable for catalysis. Dispersion of the catalytic material inthe inner adsorption area of the zeolite was achieved by variousprocesses such as (l) impregnation with an aqueous solution of a metalsalt, followed by drying and thermal decomposition of the metalcompound, (2) cation exchange using an aqueous solution of metal saltwherein the metal forms the cation, (3) cation exchange using an aqueoussolution of a metal compound in which the metal is in the form of acomplex cation with complexing agents such as ammonia, followed bythermal decomposition of the complex, and (4) vapor deposition of themetal or compound of the metal in the zeolite.

It has now been found that not only is dispersion in the inneradsorption area of the zeolite not essential, but that hydrocrackingactivity of the catalyst is greater when the hydrogenating component isincorporated in the zeolite in such a manner as to avoid impregnationinto the inner adsorption area of the zeolite crystallites or particles.Although the reason for the greater activity of the catalysts of thepresent invention is not known with certainty, it is believed that theeffect may be due to greater concentration of the hydrogenationcomponent on the exterior surface of the zeolite and, hence, its greateravailability for catalyzing the hydrocracking reaction. Also, it appearsin some cases that soluble molybdenum or tungsten compounds added to thezeolite by impregnation tend to destroy the zeolite crystal structureand acidity during the subsequent drying and calcination steps.

DETAILED DESCRIPTION According to the invention, the desired dispersionof the Group VIB metal hydrogenation component is achieved by adding itto the zeolite in a finely divided but essentially undissolved form. Asdisclosed in my copending parent applications cited above, this may beachieved in several ways, chiefly the following.

1. A relatively insoluble compound of the Group VIB metal may be mixedwith the zeolite in the presence of water. Examples of suitablecompounds are molybic oxide, tungsten oxide, tungstic acid, ammoniumceric dodecamolybdate, etc. The mixing may consist of stirring, mulling,grinding, or any conventional procedure for obtaining an intimatemixture of solid materials. Mulling or grinding may be carried out inany conventional apparatus such as a pan muller, ball mill, pug mill orcone mixer for a period of time sufficient to intimately mix the GroupVIB metal compound and the zeolite and to reduce the particle size ofthe two if desired. Mulling or grinding for a period of about 10 to 30minutes with resultant reduction of average particle size to about 0.5 5microns is normally sufficient.

The optimum amount of water may vary widely, depending on the type ofmixing, the type and particle size of the Group VIB metal compound andthe zeolite, etc. Although several of these compositions, i.e., molybdicacid and tungstic acid, are fairly soluble in water, particularly atelevated pH levels, only minor amounts, i.e., less than 10 percent, aresolubilized and deposited inside the aluminosilicate unless largeamounts of water are employed, and mulling or mixing in the presence ofexcess water is continued for an extended period. Nevertheless, severalprecautions can be taken to avoid deposition of the active metals withinthe zeolite. One of these is the maintenance of a relatively low pH,preferably within the range of 3 to about 5, during the mixing in thepresence of water so as to assure the insolubility of the otherwiseslightly soluble additives.

Following the mixing, the water content of the mixture is suitablyadjusted to provide an extrudable paste, preferably in combination witha binder such as silica or alumina. The mixture is then extruded orpelleted, dried and calcined, according to conventional procedures.

2. A soluble Group VIB metal compound may be mulled or ground with thezeolite, provided the mixture is dry or contains insufficient water todissolve an appreciable amount of the soluble compound. Examples ofsuitable soluble compounds are ammonium heptamolybdate, ammoniumdimolybdate, ammonium paratungstate, ammonium sulfotungstate, etc.However, as in the previous case involving addition of insolublecompounds, care should be taken to assure the formation of a finelydispersed form of the calcined active metal component. All of thesoluble compounds considered in this embodiment are thermallydecomposable and become more dispersed upon calcination due tofragmentation and conversion to a different chemical form. Nevertheless,care should be taken to assure a relatively even fine particle sizedistribution of the starting materials, i.e., the ammoniumheptamolybdate, paratungstates, etc., during the mulling or mixing step.This objective can be easily accomplished by employing finely dividedstarting materials usually having particle sizes below about 300microns, preferably less than about 200 microns. The particle size ofthese materials is further reduced upon mulling and, as previouslymentioned, finer dispersion results from calcination and thermaldecomposition. Promoters or stabilizers such as nickel nitrate crystalsor cobalt carbonate may be added to the mixture prior to mulling orgrinding. Following the mulling step the mixture is treated with abinder, other catalyst ingredients, pelleted, dried and calcined asabove.

3. Insoluble or undissolved Group VIB metal compounds can be formed inthe presence of the zeolite. For example, the zeolite can be slurried ina solution of ammonium molybdate or tungstate. Then the slurry isacidified to precipitate molybdic or tungstic acid. Insoluble heteropolycompounds can also be formed in a slurry of the zeolite, e.g., by addingphosphomolybdic acid to an ammonium zeolite precipitates ammoniumphosphomolybdate. Suitable insoluble combinations can also be preparedby slurrying the zeolite in an ammonium tungstate or molybdate solutionand then adding a precipitating solution which contains, e.g., adissolved Group IV metal (Titanium, zirconium or hafnium) compound.Solutions of the Group VIB component and the precipitating agent mayalso be added concurrently to a zeolite slurry with the initialacidities and proportions adjusted to obtain a pH sufficient to promoteprecipitation without destroying the zeolite. In addition, the Group IVmetal compound, preferably in the form of a hydrous oxide, may be addedto the zeolite prior to the addition of the Group VIB component. In anyevent, the hydrous oxides, e.g., the oxides of titanium, zirconium,thorium, iron, chromium or cerium, should have high isoelectric pointsand are preferably catalytically active alone or in combination with thezeolite or other active constituents. It is also presently preferredthat the pH of the media in which the Group VIB metal component is addedto the hydrous oxidealuminosilicate system be below the isoelectricpoint of the hydrous oxide, preferably within the pH range of about 3 toabout 5.

The exact mechanism or mechanisms involved in utilizing such a Group IVmetal compound for adding the Group VIB hydrogenation component is notknown. However, it is believed that the operative mechanisms may involveeither formation of an insoluble compound with the hydrogenatingcomponent or adsorption of the hydrogenating component as, for example,by means of ion exchange with a hydrous oxide of the Group IV metal. Inany event, utilization of the Group IV metal results in efficientremoval of the Group VIB hydrogenation component from solution and itsincorporation with the zeolite structure in such manner as to providethe described advantages.

These methods result in the nearly quantitative addition of the GroupVIB component to the zeolite since there is no appreciable loss due tounadsorbed materials. Consequently, the recovery of impregnatingsolutions is not necessitated. These methods also permit post-exchangeof stabilizing cations, such as cobalt or nickel, into the zeolite.

The mulling or grinding procedures, (1) and (2), can be followed by theaddition of an alumina sol or basic aluminum salts along with sufficientwater to form an extrudable paste. Mixtures which contain about aluminaon a dry weight basis usually require about 50 to 60% water to form anextrudable mixture. An excellent binder can be prepared by adding nitricacid to a 30% slurry of boehmite. Adequate peptization occurs with 0.1to 1.0 acid equivalents per mole of alumina. Acid-sensitive zeolites canbe protected by adding a suitable buffer such as nickel carbonate.However, the sol-zeolite mixture should be kept slightly acidic with pHless than 4.6 to avoid gelling the sol. A low pH is also necessary tomaintain insoluble molybdic or tungstic acid. Insoluble heteropolycompounds and titanium or zirconium molybdates also decompose anddissolve in neutral mixtures. Solubilization lowers the activity andcauses the catalyst to be similar to conventional impregnatedpreparations.

From the foregoing it will be apparent that in any of the foregoingmethods which involve the presence of a substantial aqueous phase, it isbeneficial to maintain acid conditions during the mulling and drying ofthe Group VIB-zeolite mixture. It is contemplated to maintain any pHabove the level at which destruction of the zeolite crystal structureoccurs, up to about 6. The various zeolites differ considerably in theirsusceptibility to acid attack, but normally pHs within the range ofabout 2-6, preferably 3-5 will be utilized. Although any compatible acidmay be used, it is preferred to employ acids having a monovalent anion,and especially acids having thermally decomposable anions such as nitricor acetic.

The crystalline zeolites employed herein, commonly known as molecularsieves, are aluminosilicates such as those of the Y, (includingultrastable Y) X, A, L, T, Q, and B crystal types, as well as zeolitesfound in nature such as for example mordenite, stilbite, heulandite,ferrite, chabazite, and the like. The preferred crystalline zeolites arethose having crystal pore diameters between about 6 15 A, wherein theSiO /AI O mole ratio is about 3/1 to 10/1. For most catalytic purposes,e.g., catalytic hydrocracking, it is preferable to replace most or allof the zeolitic alkali metal cations normally associated with suchzeolites with other cations, particularly hydrogen ions and/orpolyvalent metal ions such as cobalt, nickel, magnesium, zinc, rareearth metals, and the like. A particularly desirable form of zeolite isa stabilized hydrogen Y zeolite prepared by first exchanging a majorproportion of the zeolitic sodium ions with ammonium ions, thencalcining the partially exchanged material in the presence of steam attemperatures of about 700 to l200F., then reexchanging the once-calcinedmaterial with ammonium salt to reduce the sodium content to below about0.5 weight-percent. The resulting ammonium zeolite is then mixed with ahydrous alumina binder and the desired hydrogenating metals, pelleted orextruded, and again calcined. The unit cell constant of the Y zeolitestabilized in this manner is between about 24.45 and 24.6 A.

Another particularly desirable type of zeolite for use herein isdescribed in my copending application Ser. No. 761,321. It is preparedby exchanging into a suitable zeolite, particularly Y zeolite, astabilizing proportion of a Group VIII metal, particularly nickel or C0-balt, and then calcining the resulting metal zeolite prior to additionof the Group VIB metal component. Calcining the aluminosilicateintermediate the addition of the Group VIII and the Group VIB componentsso modifies the characteristics of the combination that the resultantcomposition exhibits activity superior to that exhibited by catalystsprepared without intervening calcination.

The Group VIB metals employed herein comprise chromium, molybdenum, andtungsten or any combination thereof, preferably molybdenum and/ortungsten, in the form of their oxides or sulfides. Amounts of the GroupVIB hydrogenation component will usually range from about 1 percent to20 percent by weight of the final composition, based on free metal.Generally, optimum proportions will range between about 5 percent and 15percent. Molybdenum in the form of the sulfide is especially preferredas the hydrogenation component, preferably in combination with nickelorcobaltstabilized zeolites.

Although as noted above, it is preferred to add the stabilizingcomponent, e.g., nickel or cobalt, to the zeolite, and calcine theresulting composition prior to addition of the Group VlB component, itis also contemplated that the stabilizing metal may be added after orsimultaneously with addition of the Group VIB component. Proportions ofthe nickel or cobalt will range from about 2 percent to percent byweight, with the preferred range being from about 4 to 8 percent. Thepartial solubility of the Group VlB component precursor in someembodiments also renders it advisable to incorporate the stabilizingcation before adding the particulate molybdenum or tungsten compoundwith intermediate drying and/or calcination. This procedure limits lossand solubilizing of the Group VIB component.

Following incorporation of the metal constituents into the zeolite thecomposite is pelleted or otherwise treated to obtain catalyst particlesof the size and shape desired for the reaction to be catalyzed. Forhydrocracking processes, pellets of the type described in the examplesbelow are generally suitable. A binder or matrix material is desirablyincorporated in, or admixed with,'the metal-zeolite composite prior topelleting in order to increase the resistance of the final catalystparticles' to crushing and abrasion. Silica, introduced in the form of asol, is very satisfactory for this purpose; however, other oxides suchas alumina or mixed oxides such as silica-alumina, silica-zirconia, etc.may also be used. A particularly preferred material is Ludox silica sol,described in U.S. Pat. Nos. 2,574,902 and 2,597,872. Another preferredmaterial is alumina hydrogel.

The catalyst pellets are then dried and activated by calcining in anatmosphere that does not adversely affect the catalyst, such as air,nitrogen, hydrogen, helium, etc. Generally, the dried material is heatedin a stream of dry air at a temperature of from about 500F. to 1500F.,preferably about 900F., for a period of about 0.5 to 16 hours,preferably about 2 hours, thereby converting the metal constituents tooxides.

In addition, the catalysts are preferably further activated bypresulfiding with a sulfide such as hydrogen sulfide to convert themetal constituents of the catalyst to sulfides. This is readilyaccomplished, e.g., by saturating the catalyst pellets with hydrogensulfide for a period of from 1 to 4 hours. This procedure is describedin more detail in US. Pat. No. 3,239,451.

The hydrocracking feedstocks which may be treated using the catalysts ofthe invention include in general any mineral oil fraction boiling abovethe conventional gasoline range, i.e.. above about 300F. and usuallyabove about 400F., and having an end-boiling-point of up to about1,000F. This includes straight-run gas oils and heavy naphthas, cokerdistillate gas oils and heavy naphthas, deasphalted crude oils, cycleoils derived from catalytic or thermal cracking operations, etc. Thesefractions may be derived from petroleum crude oils, shale oils, tar sandoils, coal hydrogenation products, etc. Feedstocks boiling above about480F., preferably between about 400 and 650F., having an API gravity of20 to 35, and containing at least about 30 percent by volume ofacid-soluble components (aromatics olefins) are generally employed. Allof these feeds are known to contain substantial amounts of aromaticcompounds which are hydrogenated and hydrocracked only with considerabledifficulty. As demonstrated by the examples hereinafter detailed thecatalysts of this invention are much more effective in hydrogenating andhydrocracking heavier aromatic compounds such as naphthalenes, indanes,tetralins and the like. These catalysts are therefore particularlyeffective for converting feeds containing 10 volume percent, generallyin excess of 30 volume percent of aromatics to gasoline and midbarrelfuels.

Conversion conditions effective for promoting hydrogenation orhydrocracking generally comprise temperatures of about 500 to about900F., hydrogen partial pressure of about 400 3000 psig, hydrogen ratiosof about 1,000 to 15,000 scf/b, and liquid hourly space velocitiesranging between about 0.5 and 5.

While the foregoing description has centered mainly on hydrocrackingprocesses, the catalysts described are also useful in a great variety ofother chemical conversions, and generally, in any catalytic processrequiring a hydrogenating or acid function in the catalyst. Examples ofother reactions contemplated are hydrogenation, alkylation (ofisoparaffins with olefins, or of aromatics with olefins, alcohols oralkyl halides), isomeri- Zation, polymerization, reforming(hydroforming), desulfurization, denitrogenation, carbonylation,hydrodealkylation, hydration of olefins, transalkylation, etc.

The following examples will serve to more particularly illustrate thepreparation of the catalysts of the invention and their advantageousproperties in hydrocracking operations.

Examples l-4 and Table 1 show a comparison of four catalysts withsimilar compositions and zeolitic stabilities. The conventionalpreparation of Example 1, prepared by impregnation, had the lowesthydrogenation and hydrocracking activity. The three catalysts ofExamples 2, 3 and 4, prepared by combining insoluble forms of molybdenumwith cobalt zeolite Y, all gave similar higher hydrocracking andhydrogenation conversions, as shown in Table 1.

All four catalysts were made from the same batch of cobalt zeolite Y.The cobalt zeolite was prepared by slurrying 560 g ammonium zeolite Y in500 ml water, adding 500 ml 1.5M CoCl and heating to boiling for 1 hour.Then the slurry was filtered, washed and the exchange repeated. Afterthe second exchange the zeolite was washed free of chloride and driedovernight at 220F. Four g portions of the cobalt zeolite were treatedaccording to Examples 14.

EXAMPLE 1 The zeolite powder was mixed with 126 ml Ludox LS 30% silicasol. Then 36 ml 1.7M Co(NO was added as a coagulant. The paste was castinto 0.094 X 0.020- inch pellets, dried at 220F. and calcined 2 hours at600F. The calcined pellets were immersed for one hour in ml of 1.04M(NI-10 M00 Then the pellets were drained, dried at 220F. and recalcined2 hours at 600F. Next the pellets were spread in a thin layer and theremaining drained molybdate solution was poured evenly over the pellets.The remainder of the solution was completely adsorbed. Then the pelletswere redried and finally calcined at 900F.

EXAMPLE 2 The cobalt zeolite Y powder, 120 g, was dry mixed with 23.3 gmolybdic oxide for 30 minutes to a 12-inch pan muller. Then the mixturewas added to 126 ml 8 test conditions were: 650F., 1000 psig, 2.0 LHSVand 6000 CF H G.

""lmpregnation with ammonium molybdate solution. "Mulled with insolublemolybdic oxide. "Mulled with insoluble ammonium phosphomolybdate.

Ludox LS and 36 ml 1.7M C(NO and formed into pellets as in Example 1.The pellets were dried and then calcined at 900F.

EXAMPLE 3 The cobalt zeolite Y powder, 120 g, was mixed with 80 ml waterand 23.3 g molybdic oxide powder. The mixture was stirred for 20 minutesand then dried overnight at 220F. The dried cake was granulated througha 60 mesh screen before mixing with 126 ml Ludox LS and 36 ml 1.7M Co(NOThe resulting paste was formed into pellets, dried, and calcined as inExamples 1 and 2.

EXAMPLE 4 Ammonium phosphomolybdate was prepared as follows. A molybdatesolution was prepared by dissolving 85.2 g (NH Mo O .4l-I O in 390 mlwater. Then 85 ml N HNO was added. A phosphate solution was prepared bydissolving 21.2 g (NI-l HPO in 85 ml water and 42 ml l5N HNO Thephosphate solution was slowly added to the molybdate solution. Ten themixture was allowed to stand minutes, chilled and decanted. The pH wasadjusted to 2.0 with 3N NH OH. Then the slurry was filtered, washed withice water, and pressed out to a firm cake. The ammonium phosphomolybdatecontained 31.3% volatile material when a sample was calcined at 1000F.

Cobalt zeolite Y, 120 g, was mixed with 76 ml water and 35.5 g ofammonium phosphomolybdate filter cake. The mixture was stirred for 20minutes and then dried overnight at 220F. The dried cake was granulatedthrough a 60 mesh screen before mixing with 126 ml Ludox LS and 36 ml1.7M CO(NO3)2. The resulting paste was formed into pellets, dried andcalcined as previously.

The feed used in the tests was a synthetic gas oil 50-50 blend oftetralin and mineral oil by volume boiling between 400 and 812F., havingan AP! gravity of 24.6 and containing 1.0 weight-percent sulfur. As themineral oil was a paraffinic stock, only 50 volume percent of the feedmolecules contained aromatic nuclei and these molecules, i.e., tetralin,were not completely aromatic. These factors tend to complicatedetermination of aromatic conversion by product analysis. The

Examples 5-8 and Table 2 further demonstrate the adverse effect ofmolybdenum solvation on hydrocracking activity. The catalyst of Example5, made by impregnating nickel zeolite Y with a solution of ammoniumheptamolybdate, was inferior to that of Example 6, made by acidifying amolybdate solution and mixing with the zeolite. Example 8 shows theadverse effect of decomposing and dissolving ammonium phosphomolybdatein the presence of nickel zeolite Y. Higher hydrocracking conversionsand improved denitrogenation occurred when the molybdenum solubility wasdecreased through the use of ammonium phosphomolybdate (Example 7) orthe formation of molybdic acid (Example 6).

The catalysts of Examples 5-8 were all made from one batch of nickelzeolite Y. The preliminary nickel exchange consisted of mixing 550 gammonium zeolite Y (1.6% Na O) with one liter of 1.0 M nickel chloride,heating to 200F., allowing to cool, filtering and washing free ofchloride. This exchange was repeated twice. After the final wash theproduct was dried overnight at 200F. The loss on ignition was 17.6% andthe nickel content was 8.5% NiO on a calcined basis. One hundred gramportions of this material were used to prepare the four catalysts of theexamples. The following quantities of components were added to each ofthe catalysts:

Ammonium heptamolybdate, 26.0 g, containing 82% M00 Ludox LS silica sol,112 m, containing 0.36 g Si- Nickel oxide, 4.1 g, was added as 1.7 Mnickel nitrate (0.127 g NiO/ml) or as 1.7 M nickel nitrate and nickelcarbonate powder. When nickel carbonate was added the nickel nitrate wasdecreased to keep the same total number of equivalents.

A small quantity of phosphorus, approximately 0.8 g P 0 was added aspart of the phosphomolybdate complex to catalysts prepared by the methodof Examples 7 and 8.

EXAMPLE 5 The nickel zeolite Y powder was mixed with the Ludox LS and 32ml 1.7M nickel nitrate. The paste was cast into pellets, dried, andcalcined at 600F. for 1 hour. The calcined pellets were immersedovernight in a solution of the ammonium heptamolybdate in 150 ml water,drained, dried and recalcined at 600F. A small amount of nickelmolybdate precipitated during the impregnation due to nickel-ammoniumexchange. After the second calcination the pellets were spread in a thinlayer and allowed to absorb the remainder of the impregnation solution.Next, the catalyst was activated by calcining overnight at 900F. in dryflowing air and then saturated with hydrogen sulfide at roomtemperature.

EXAMPLE 6 The ammonium heptamolybdate was dissolved in 100 ml water.Sufficient 3N nitric acid was added to lower the pH to 4.0 andprecipitate the molybdate prior EXAMPLE 8 The same procedure andquantities used in Example 7 were repeated, except for the pHadjustment. The pH of the slurry was increased from 4.9 to 6.7 by theaddition of a small amount of ammonium hydroxide prior to evaporating onthe steam bath.

The hydrocracking activity comparisons shown in Table 2 were determinedusing a gas oil feed with the following characteristics:

Gravity 249 AP] Boiling Range 455890F. Sulfur Content 1.05 wt-% NitrogenContent 0.233 wt-% The test conditions were 800F., 1400 psig, 2.0 LHSV,and 12,000 CF H /B.

"During molybdenum addition.

"Added as soluble ammonium heptamolybdate. "'Added as insolubleacidified molybdate. "Added as insoluble acidified phosphomolybdate.""Added as soluble phosphomolybdate at high pH.

to contact with the aluminosilicate. The nickel zeolite 40 Y powder wasslurried with this solution, allowed to stand overnight, and then driedon a steam bath. The dried powder was mixed with the Ludox LS and 32 ml1.7M nickel nitrate. The paste was formed into pellets and activatedaccording to the procedure of Example EXAMPLE 7 The ammoniumheptamolybdate was dissolved in 130 ml water. Then 25 ml concentratednitric acid was added. A phosphate solution was prepared by dis solving6.5 g diammonium phosphate in 25 ml water and 13 ml concentrated nitricacid. The phosphate solution was slowly added to the molybdate solutionand then allowed to stand 20 minutes. The ammonium phosphomolybdateprecipitate was collected by centrifuging and washed with 50 ml water.The washed precipitate was reslurried in 80 ml water. Powdered nickelcarbonate, 2.9 g, was added as a buffer which would not decompose thephosphomolybdate complex while protecting the zeolite from strongacidity. The nickel zeolite Y powder was added to the slurry. The pH ofthe combination was 4.9. Next, the slurry was dried on a steam bath andthe dried powder was mixed with the Ludox LS and 18 ml 1.7M nickelnitrate. The paste was formed into pellets and activated according tothe previous examples.

Examples 9 and 10 and Table 3 compare two parallel nickelmolybdenazeolite Y catalysts. This comparison again shows the favorable effect ofacidifying the molybdate solution to form relatively insoluble molybdicacid. The feed and test conditions were the same as those used inExamples 5 to 8.

EXAMPLES 9 & l0

Ammonium heptamolybdate, 20.7 g, was dissolved in ml water and the pHwas adjusted to 7.0 with l5N NH OH. Ammonium zeolite Y powder, 100 g,was then added and the mixture stirred and evaporated to a pastyconsistency on a steam bath. 27 ml of 1.7M nickel nitrate was added andthe mixture was stirred and dried on a steam bath. The dried materialwas then granulated and mixed with 1 13 ml of Ludox LS and 32 ml 1.7Mnickel nitrate. This mixture was then cast into 0.094 X 0.020-inchpellets, dried and calcined at 900F. The same procedure was employed forExample 10 except that the pH was initially adjusted to 4.0 with l5N HNOTable 3-Continued Ex. 9 Ex. 10

Residual Sulfur. wt-7r 0.091 0.040 Residual Nitrogen, wt-7r 0.045 0.035

Although lowering the pH, as illustrated in the above examples, is aneffective way of decreasing the solubility of molybdates, tungstates,etc., an even more quantitative removal from solution can be achieved byuse of an adsorbing or precipitating agent in the catalyst preparation.Insoluble hydrous oxides of metals such as titanium, zirconium, thorium,iron and chromium have been found to be particularly effective for thispurpose. The hydrous oxide, in addition to being insoluble, should havea high isoelectric point and should form a catalytically activecombination with the hydrogenation component. Addition of thehydrogenation component should be effected at a pH that is below theisoelectric point of the hydrous oxide. This pH value will generally bein the range of about 3 to 5. Examples l1-l4 and Table 4 illustratepreparation and activity for catalysts using titanium or zirconium foradsorption or precipitation of molybdates into zeolite catalysts.

EXAMPLE 1 1 The titania gel used in this example was prepared by adding25 ml 4M TiCl, solution to 250 ml 2.4N ammonium hydroxide. The gel wascollected by filtration, washed free of chloride, and then dried for 2hours at 400F. A 6.2 g portion of the dried gel was mulled with 100 gammonium zeolite Y. The mulled powder mixture was slurried in 215 ml of0.69M ammonium molybdate. The pH was adjusted to the interval 3.6 3.8with nitric acid. After two days the solids were collected byfiltration. The dissolved molybdena was recovered by evaporating thefiltrate and calcining the residue 2 hours at 700F. The weight of theresidue, 7.4 g, indicated that approximately 65% of the originalmolybdate had been adsorbed on the titania gel-zeolite mixture. Next,the recovered 7.4 g of molybdena was added back to the catalyst bymulling with the zeolite mixture. Nickel was exchanged into thiscombination by slurrying with 62 ml 1.0M nickel nitrate, allowing tostand overnight, and filtering. The filter cake was dried, mixed with115 ml Ludox LS 30% silica sol and 36 ml 1.7M nickel nitrate, cast intopellets, and calcined at 900F.

EXAMPLE 12 The titania in this example was formed in situ by addingsolutions of titanium chloride and ammonium hydroxide concurrently tothe zeolite slurry. This procedure gives an improved molybdenadistribution and is easier to handle during washing. Removal of chlorideions by washing improves the subsequent adsorption of molybdic acid. ThepH must be lower than the isoelectric point of titania during theadsorption of molybdena. The specific procedure was as follows:

To 100 g of ammonium zeolite Y was added 370 ml of 0.2M TiCl andsufficient 3N NH OH to maintain the pH in the range 3.5 3.9. The slurrywas then filtered and the residue washed with water and slurried in 177ml of 0.69M ammonium molybdate solution. The resulting mixture was aged2 days at room temperature and filtered. The dissolved molybdena wasrecovered by evaporating the filtrate and calcining the residue 2 hoursat 700F. The weight of residue, 2.3 g, indicated that approximately 87%of the original molybdate had been adsorbed on the titania-zeolitecombination. Next, the recovered 2.3 g of molybdena was added back tothe catalyst by mulling with the zeolite combination. Nickel wasexchanged into the catalyst by slurrying with 59 ml 1.0M nickel nitrate,allowing to stand overnight, and filtering. The filter cake was dried,mixed with 111 ml Ludox LS and 35 ml 1.7M nickel nitrate, cast intopellets, and calcined at 900F.

EXAMPLE 13 The catalyst of this example was made by concurrently addingtitanium and molybdenum solutions to the zeolite slurry. The proportionswere adjusted during this addition to keep the pH less than 4.0 since aneutral or high pH would have caused the molybdenum to remain insolution. The specific procedure was as follows:

A g portion of ammonium zeolite Y was slurried in 200 ml water. Ammoniummolybdate, 177 ml 0.69M solution, and TiCl 370 ml 0.2M solution, wereadded concurrently to this slurry. Sufficient 3N ammonium hydroxide wasalso added to maintain the pH in the range 3.5 3.9. The resultingcombination was aged two days at room temperature and filtered. Thedissolved molybdena was recovered by evaporating the filtrate andcalcining the residue 2 hours at 700F. The weight of residue, 2.8 g,indicated that approximately 85% of the original molybdate had beenadsorbed or precipitated on the titania-zeolite combination. Next, therecovered 2.8 g of. molybdena was added back to the catalyst by mullingwith the zeolite combination. Nickel was exchanged into the catalyst byslurrying with 59 ml 1.0M nickel nitrate, allowing to stand overnight,and filtering. The filter cake was dried, mixed with 111 ml Ludox LS and35 ml 1.7M nickel nitrate, cast into pellets, and calcined at 900F.

EXAMPLE 14 The catalyst of this example was made by alternate additionof titanium, molybdenum and zirconium. The final extra addition ofzirconyl chloride considerably lowered the molybdate concentration inthe filtrate (only 6.7% of the molybdenum remained dissolved after thezirconium addition). The specific procedure was as follows.

A 438 g portion of ammonium zeolite Y was slurried in 530 ml water. TiCl980 ml 0.2M solution, was added to the slurry concurrently withsufficient 3N ammonium hydroxide to maintain the pH in the range 3.53.9. The solids were collected by filtration, washed free of chlorides,and then slurried in 470 ml 0.69M ammonium molybdate. Next, ml 0.2MTiCl, and 200 ml 1.0M zirconyl chloride were added concurrently withsufficient 3N ammonium hydroxide to maintain 3.5 3.9 pH. Then thedissolved molybdena was determined by filtering, evaporating thefiltrate, and calcining the residue 2 hours at 700F. The weight of theresidue, 3.2 g indicated that approximately 93% of the originalmolybdate had been adsorbed or precipitated on thetitania-zirconia-zeolite combination. Next, the recovered 3.2 g ofmolybdena was added back to the catalyst by mulling with the zeolitecombination. Nickel was exchanged into the catalyst by slurrying with ml1.0M nickel nitrate, allowing to stand overnight, and filtering. Thefilter cake was dried, mixed with 295 ml Ludox LS and 93 ml 1.7M nickelnitrate, cast into pellets, and calcined at 900F.

The data in Table 4 compare the hydrocracking and a pan muller for 30minutes. Then 67 g of an acidic 30% alumina sol was added to provide 20%A1 binder on a dry basisNitric acid in the alumina so] lowered the pH ofthe final mixture to 4.4. The paste mixhydrogenation activities of thecatalysts of Examples 5 ture was extruded as l/l6-inch rods, dried, andactill-l4. The feed and test conditions used in testing vated bycalcining at 900F. these catalysts were the same as those used fortesting the catalysts of Examples 1 to 4. The catalyst of Exam- EXAMPL El6 ple 14, in which the molybdenum formed the least solu- A m of thecobalt Zeohte Y used Example 15 ble combination with titanium andzirconium, was the f calcmfid 16 hours at q Then 61 g of the mostactive. The catalyst of Example 13, made by concmed Zeohte was mulledwlth g s)2- 2 current additions, and that of Example 12, made by adand183 g (N OG 1 24- 2 Crystals in a P sorption on the in-situ titania,showed intermediate mhher for 30 hhhutes- Next, 67 g of an acidic 30%amounts of dissolved molybdena. These two catalysts hhha 9 was added toProvide 20% 2 3 binder On 3 also had intermediate activities. Thecatalyst prepared dry basls- 1 acid in the alumina 501 lowered the Pwith the separately prepared titania gel, that of Examof the finalmlxliure to The PaSte mixture was ple 11, had the largest amount ofdissolved molybdef f as 1/16'Inch rods, dried, and activated y num andthe lowest activity. These results are consisclhlhg at 90001:- tent withthe data in Tables 1, 2, and 3, i.e., combining Tab] 5 e or forminginsoluble molybdena with the zeolite gives greater activity. Thecatalyst of Example 1, prepared by Example 15 Example impregnating withcompletely dissolved ammonium Activity Data molybdate, was the leastactive catalyst tested. Mulling Hours on stream 248 248 with insolubleforms of molybdenum gave appreciable 352 v 65 improvement, as shown bythe catalysts of Examples 2, z i z' gg' gs of Feed 52 65 3 and 4.Forming insoluble molybdates in the presence Aromatics, vol-7r 25 of thezeolite gave the highest activities, as shown by Olaf-"15901172 O 0 thecatalysts of Examples 12, 13 and 14. saturates 101% 65 75 Table 4Example 11 Example 12 Example 13 Example 14 Composition %MoO 12.7 11.010.4 9.3 %NiO 6.5 5.8 5.9 4.0 %TiO 4.5 3.3 3.5 4.0 7vZrO 5.6 pH 3.6-3.83.5-3.9 3.5-3.9 3.5-3.9

Activity Data Hours on Stream 3-19 2-18 2-18 2-18 APl 34.7 38.5 40.341.8 400F. Conv.,

vol-7c of Feed 51 59 62 73 Gasoline Comp.

Aromatics, vol-71 42 31 28 25 Olefins, vol-% 0 0 0 0 Saturates, vol-7r58 69 72 75 As described above, soluble components can be used 1 claim:to prepare highly active zeolite catalysts provided there 1. Ahydrocarbon conversion catalyst comprising a is insufficient water todissolve the Group VlB compocrystalline aluminosilicate zeolite baseintimately comnent. The catalysts of the following Examples 15 andposited with at least one finely divided Group VlB 16, were made bymulling cobalt zeolite Y powder with metal hydrogenating component, saidhydrogenating crystals of nickel nitrate and ammoniumheptamolybcomponent or a precursor thereof having been initially date.Then, after the mixture was uniform, a 30% alucomposited with saidzeolite base in a substantially unmina sol was added in an amount toprovide 20% A1 0 dissolved particulate form by intimately admixing thebinder on a dry basis. The pH of the extrusion pastes two components inan aqueous medium having a pH were 4.4 and 3.9 for Examples 15 and 16,respectively. below 5, but sufficiently high to avoid acid destructionThis acidity, by forming molybdic acid, suppressed the of the zeolitecrystal structure. tendency of molybdenum to dissolve. The catalyst of2. A catalyst as defined in claim 1 wherein the pH of Example 16, madewith 900F. calcined cobalt zeolite said aqueous medium is between about3 and 5- had the highest hy r cracking activity and P 6O 3. A catalystas defined in claim 1 wherein said zeoduced fewer light hydrocarbons peramount of gasolite base is a nickelor cobalt-stabilized Y zeolite. line.Results are shown in Table 5. The feed and test 4. A catalyst as definedin claim 1 wherein said zeoconditions were the same as those used intesting the lite is a steam-stabilized hydrogen Y zeolite. catalysts ofExamples 1 to 4. 5. A catalyst as defined in claim 1 wherein saidhydrogenating component is initially admixed with said EXAMPLE 15 A 73 gportion of cobalt zeolite Y, which contained 16.3% adsorbed water, wasmulled with 19.5 g Ni(- NO ).61-l O and 18.3 g (NI-1 MO7O24.4H2Ocrystals in zeolite base in the form of molybdenum oxide and/or tungstenoxide.

6. A catalyst as defined in claim 1 wherein said hydrogenating componentis initially admixed with said l l6 zeolite base in the form of ammoniumheptamolybdate 9. A catalyst as defined in claim I wherein: and/orammonium phosphomolybdate. l. A cobalt and/or nickel hydrogenatingcomponent 7. A catalyst as defined in claim 1 wherein said h yand analumina gel binder are composited with the drogfinatmg Componfintmftlany admlxed Wlth 531d zeolite base and the Group VlB metal componentzeolite base in the form of an Insoluble complex of mo- 5 in saidaqueous medium; y f or tungstate 1on5 Wlth at least one hydrous 2. thepH of said aqueous medium is between about oxide of a metal selectedfrom the class consisting of 3 and s g t t g g z m i 9 h 3. the zeolitebase is a steam-stabilized hydrogen Y Ca a ys as 8 me 0 mm w erem Sal yzeolite, a nickel-stabilized Y zeolite, or a cobaltdrogenating componentis initially admixed with said 10 stabilized Y zeolite, and

zeolite base in the form of ammonium heptamolybdate, 4 said Group VIBmeta] hydrogenatin com Onem and wherein a hydrous oxide of zirconium,titanium, a molybdenum sulfide g p chromium, thorium or iron isseparately added to the mixture.

1. A HYDROCARBON CONVERSION CATALYST COMPRISING A CRYSTALLINEALUMINOSILICATE ZEOLITE BASE INTIMATELY COMPOSITED WITH AT LEAST ONEFINELY DIVIDED GROUP VIB METAL HYDROGENATING COMPONENT, SAIDHYDROGENATING COMPONENT OR A PRECURSOR THEREOF HAVING BEEN INITIALLYCOMPOSITED WITH SAID ZEEOLITE BASE IN A SUBSTANTIALLY UNDISSOLVEDPARTICULATE FORM BY INTIMATELY ADMIXING THE TWO COMPONENTS IN AN AQUEOUSMEDIUM HAVING A PH BELOW 5, BUT SUFFICIENTLY HIGH TO AVOID ACIDDESTRUCTION OF THE ZEOLITE CRYSTAL STRUCTURE.
 2. A catalyst as definedin claim 1 wherein the pH of said aqueous medium is between about 3 and5.
 2. the pH of said aqueous medium is between about 3 and 5;
 3. thezeolite base is a steam-stabilized hydrogen Y zeolite, anickel-stabilized Y zeolite, or a cobalt-stabilized Y zeolite; and
 3. Acatalyst as defined in claim 1 wherein said zeolite base is a nickel- orcobalt-stabilized Y zeolite.
 4. A catalyst as defined in claim 1 whereinsaid zeolite is a steam-stabilized hydrogen Y zeolite.
 4. said Group VIBmetal hydrogenating component is a molybdenum sulfide.
 5. A catalyst asdefined in claim 1 wherein said hydrogenating component is initiallyadmixed with said zeolite base in the form of molybdenum oxide and/ortungsten oxide.
 6. A catalyst as defined in claim 1 wherein saidhydrogenating component is initially admixed with said zeolite base inthe form of ammonium heptamolybdate and/or ammonium phosphomolybdate. 7.A catalyst as defined in claim 1 wherein said hydrogenating component isinitially admixed with said zeolite base in the form of an insolublecomplex of molybdate or tungstate ions with at least one hydrous oxideof a metal selected from the class consisting of zirconium, titanium,chromium, thorium and iron.
 8. A catalyst as defineD in claim 1 whereinsaid hydrogenating component is initially admixed with said zeolite basein the form of ammonium heptamolybdate, and wherein a hydrous oxide ofzirconium, titanium, chromium, thorium or iron is separately added tothe mixture.
 9. A catalyst as defined in claim 1 wherein: